1. Field of the Invention
The present invention relates to an image exposure apparatus in which a sheet material, such as a photosensitive planographic printing plate, is exposed so that an image is formed thereon.
2. Description of the Related Art
In general, a printing plate which includes a support formed of a thin aluminum plate and a photosensitive layer formed on the support is used in printing. After an image has been formed on this printing plate by exposure, the exposed printing plate is subjected to a development processing, and a printing plate which is ready for printing is thereby formed.
In an image exposure apparatus which carries out image exposure on this printing plate, a plurality of printing plates are loaded in a cassette in a superposed manner. These printing plates are taken out from this cassette one at a time and are subjected to image exposure. Further, the size of the printing plate is selected so as to correspond to the size of a material to be printed. For this reason, in the image exposure apparatus, image exposure can be performed on printing plates having different sizes (for example, those in the range of 1030 mm (length)xc3x97950 mm (width) to 500 mmxc3x97400 mm, or the like). Furthermore, the image exposure apparatus is structured in such a manner that printing plates having various sizes are loaded into a cassette, and after a printing plate having a desired size has been taken out from the cassette, image exposure is carried out on the printing plate.
One type of the image exposure apparatus is structured such that a printing plate is made to closely contact the outer peripheral surface of a rotating drum. In this type of the image exposure apparatus, while sub-scanning is carried out by rotating the printing plate together with the rotating drum, image exposure is carried out on the printing plate by a light beam emitted from an exposure head which is disposed opposite to the rotating drum.
The support of the printing plate has a thickness of 0.3 mm and therefore is very thin, and the photosensitive layer is brittle. For this reason, when the printing plate is curved at a small curvature, cracks or the like are inevitably formed in the photosensitive layer. Accordingly, in the image exposure apparatus in which image exposure is carried out in such a manner that the printing plate is wound onto the outer peripheral surface of the rotating drum, the printing plate which has been taken out from the cassette needs to be conveyed such that, as far as possible, the printing plate is not curved.
For example, in a conventional image exposure apparatus 200 illustrated in FIG. 12A, cassette loading sections 206A and 206B are disposed adjacent to a recording section 204 which effects image exposure on a printing plate 202. A plate-supplying conveyor 208 is disposed at the upper side of the cassette loading sections 206A and 206B. The plate-supplying conveyor 208 conveys, in a substantially horizontal manner, the printing plate 202 which is taken out from the cassettes 210 each loaded in the cassette loading sections 206A or 206B, and supplies the printing plate 202 to the recording section 204.
A plate-discharging conveyor 212 is disposed above the plate-supplying conveyor 208. The plate-discharging conveyor 212 conveys the printing plate 202 which has been taken out from the recording section 204 after completion of image exposure and sends it out to an automatic development apparatus 214 which is provided outside the image exposure apparatus 200. The image exposure apparatus 200 is an inner spinner type in which the printing plate 202 is exposed while closely contacting the inner peripheral surface of a drum 216.
In the image exposure apparatus 200 in FIG. 12A, by loading the cassettes 210 at a relatively gentle angle (at an angle close to 180xc2x0) and conveying the printing plate 202 substantially horizontally by the plate-supplying conveyor 208, image exposure can be carried out while curving of the printing plate 202 is suppressed. Moreover, the height of the apparatus 200 can be made relatively low.
On the other hand, in an image exposure apparatus 220 shown in FIG. 12B, a cassette loading section 224 is provided adjacent to a recording section 222. Cassettes 226 are disposed substantially upright at the cassette loading section 222. Plate-supplying carriers 228 and a plate-discharging carrier 230 are provided so as to convey printing plates 202 in a substantially upright manner.
In the image exposure apparatus 220 in FIG. 12B, the printing plate 202 which has been pulled out upward from the cassette 226 is conveyed by the plate-supplying carrier 228 and supplied to the recording section 222. Further, the printing plate 202 which has been subjected to image exposure is pulled upwards from the recording section 222, and is held and discharged to the outside of the apparatus 220 by the plate-discharging carrier 230. In this image exposure apparatus 220, the printing plate 202 is wound onto the outer peripheral surface of a rotating drum 232 which is provided at the recording section 222, and scanning exposure is effected on the printing plate 202 by rotating the printing plate 202 together with the rotating drum 232.
This image exposure apparatus 220 is structured such that the cassettes 226 are loaded substantially upright in the cassette loading section 224. Therefore, the installation space for the apparatus 220 can be made small.
In both the image exposure apparatuses 200 and 220, the printing plate 202 is curved while image exposure is carried out, and is made straight when conveyed.
However, as in the image exposure apparatus 200, in case of a structure in which the printing plate 202 is conveyed so as to be substantially horizontal, the height of the apparatus is low, but a considerably large installation space is necessary. Further, as in the image exposure apparatus 220, in case of a structure in which the printing plate 202 is conveyed so as to be substantially upright, the installation space for the apparatus is relatively small, but the height of the apparatus is considerably high. Namely, there is a drawback in that both the conventional apparatuses are large.
Further, when the printing plate which has been subjected to image exposure is taken out from the recording section and is sent out to a device for the next process such as an automatic development device, the printing plate needs to be sent out at a speed which corresponds to the speed at which the printing plate is conveyed in the device for the next process. Therefore, a space in which the printing plate is temporarily stored after image exposure thereof is needed inside the image exposure apparatus. This storage space may be an obstacle to making the apparatus compact.
As a technique relating to the present invention, Japanese Patent Application Laid-Open (JP-A) No. 5-278843 discloses a printing plate conveying apparatus which connects a printing apparatus to a development apparatus. This apparatus includes a rotating section for rotating a printing plate on a horizontal surface, a belt conveying section for conveying the printing plate in a horizontal direction, and a roller conveying section for conveying the printing plate in an opposite horizontal direction. In order to make it possible to change the conveying direction by 90xc2x0, the structure of this apparatus is large and very complicated.
An aspect of the present invention is an image exposure apparatus for carrying out image exposure on a sheet material, comprising: a recording section which records an image on the sheet material by exposing the sheet material; an accommodating section which is disposed adjacent to the recording section and accommodates a plurality of sheet materials in such a manner that the plurality of sheet materials are inclined at a predetermined angle (xcex8) relative to a horizontal plane; and a diverting section which is disposed above the accommodating section, and diverts the sheet material received from the accommodation section and conveys it to the recording section. In this apparatus, the sheet materials are accommodated in an inclined manner, and therefore, the accommodating section, and as a result, the installation area for the apparatus can be made small. Moreover, since the sheet material is diverted (the direction of the sheet material is changed), the height of the apparatus can be reduced.
The angle xcex8 of the sheet material is preferably in the range greater than or equal to 45xc2x0 to less than 90xc2x0. Preferably, the accommodating section can accommodate a plurality of cassettes disposed parallel to each other, each of the plurality of cassettes being able to accommodate the plurality of sheet materials. It is preferable that the diverting section can be selectively moved to respective positions each corresponding to an exit for sheets above the cassette. In this case, since the sheet materials can be smoothly and reasonably taken out from the plurality of cassettes, the processing capacity can be considerably improved. The diverting section preferably diverts the sheet material by conveying it in such a manner that the sheet material is curved at a predetermined radius of curvature. In this case, since the curvature of the curve of the sheet material is constant, the sheet material is not easily damaged. Preferably, the diverting section includes a diverting roller which is rotated for diverting the sheet material, and the sheet material is wound onto the outer peripheral surface of the diverting roller. In this case, the curvature of the curve of the sheet material is set by the radius of the diverting roller, and the sheet material can therefore be curved at a constant radius of curvature. The radius of the diverting roller is preferably small, but can be freely set as long as damages or the like are not caused on the sheet material. Preferably, the diverting section includes an endless conveying belt which is wound onto a predetermined range of the circumference of the diverting roller so that the sheet material is nipped between the diverting roller and the conveying belt and is conveyed thereby. In this case, since the sheet material is uniformly nipped (pressed) and smoothly curved, damages such as folds, bends, or the like of the sheet material are not easily caused. The range of the endless conveying belt which is wound onto the diverting roller preferably varies in accordance with the position of the diverting section which is selectively moved above the accommodating section. Preferably, the image exposure apparatus further comprises a discharging section which is disposed above the recording section for diverting the sheet material received from the recording section and discharging the sheet material to the outside of the apparatus. The sheet material preferably includes a support and a photosensitive layer formed on the support.
Another aspect of the present invention is an image exposure apparatus for carrying out image exposure on a sheet material, comprising: a recording section which records an image on the sheet material by exposing the sheet material; an accommodating section which is disposed adjacent to the recording section and accommodates a plurality of sheet materials in such a manner that the plurality of sheet materials are inclined at an angle (xcex8) in a range greater than or equal to 45xc2x0 to less than 90xc2x0 relative to a horizontal plane; and a diverting section which is disposed above the accommodating section, and diverts the sheet material received from the accommodation section by conveying it in such a manner that the sheet material is curved at a predetermined radius of curvature, and conveys the sheet material to the recording section. In this apparatus, since the sheet material is conveyed in such a manner that the sheet material is curved at a predetermined curvature, the possibility of damages being caused on the sheet material can be reduced.
Preferably, the diverting section includes a diverting roller which is rotated for diverting the sheet material, and the sheet material is wound onto the outer peripheral surface of the diverting roller. The diverting section preferably includes an endless conveying belt which is wound onto a predetermined range of the circumference of the diverting roller so that the sheet material is nipped between the diverting roller and the conveying belt and is conveyed thereby. It is preferable that the diverting section can be horizontally moved above the accommodating section, and the range of the conveying belt which is wound onto the diverting roller varies in accordance with the moving position of the diverting section. Preferably, the apparatus further comprises a discharging section which is disposed above the recording section for diverting the sheet material received from the recording section and discharging the sheet material to the outside of the apparatus.
Yet another aspect of the present invention is an image exposure apparatus for carrying out image exposure on a sheet material, comprising: a recording section which records an image on the sheet material by exposing the sheet material; an accommodating section which is disposed adjacent to the recording section and can accommodate a plurality of sheet materials; a diverting section which diverts the sheet material received from the accommodation section and conveys the sheet material to the recording section; and a discharging section which is disposed above the recording section for diverting the sheet material received from the recording section and discharging the sheet material to the outside of the apparatus. In this apparatus, especially the discharging section can be structured in a compact manner. Further, the installation area for and the height of the apparatus can be reduced.
Preferably, the discharging section diverts the sheet material by conveying it in such a manner that the sheet material is curved at a predetermined radius of curvature. The discharging section preferably includes a discharging roller which is rotated for diverting the sheet material, and the sheet material is wound onto the outer peripheral surface of the discharging roller. The discharging section preferably includes an endless conveying belt which is wound onto a predetermined range of the circumference of the discharging roller so that the sheet material is nipped between the discharging roller and the conveying belt and is conveyed thereby. It is preferable that the range of the endless conveying belt wound onto the discharging roller is no less than a half of the circumference of the discharging roller.